This document summarizes 15 visions for future cities from 1800 to 2015, including floating cities, underwater cities, domed cities, and a city on the moon. Some of the earlier concepts include a floating balloon city over France (1800), a planned utopia around Niagara Falls (1894), and visions of aerial or underwater cities from the 1900 Paris World Exhibition. More recent ideas encompass decentralized cities (1935), floating cities above Paris (1960s), a domed Manhattan (1960s), redeveloping Tokyo Bay (1960), and semi-submerged structures in East London (2014).